davies - organotin chemistry 2e (wiley, 2004)

Alwyn G. Davies
Organotin Chemistry
Organotin Chemistry, Second Edition. Alwyn G. Davies
Copyright
 2004 Wiley-VCH Verlag GmbH & Co. KGaA.
ISBN: 3-527-31023-1
Further Titles of Interest
H. Yamamoto, K. Oshima (Eds.)
Main Group Metals in Organic Synthesis
Two Volume Set
2004, ISBN 3-527-30508-4
N. Auner, J. Weis (Eds.)
Organonsilicon Chemistry V
From Molecules to Materials
2003, ISBN 3-527-30670-6
B. Rieger, L. S. Baugh, S. Kacker, S. Striegler (Eds.)
Late Transition Metal Polymerization Catalysis
2003, ISBN 3-527-30435-5
I. Marek (Ed.)
Titanium and Zirconium in Organic Synthesis
with a foreword of V. Snieckus
2002, ISBN 3-527-30428-2
B. Cornils, W. A. Herrmann (Eds.)
Applied Homogeneous Catalysis with Organometallic Compounds
A Comprehensive Handbook in Three Volumes
2002, ISBN 3-527-30434-7
Alwyn G. Davies
Organotin Chemistry
Second, Completely Revised
and Updated Edition
WILEY-VCH Verlag GmbH & Co. KGaA

Prof. Alwyn G. Davies
University College London
Department of Chemistry
20 Gordon Street
London WC1H 0AJ
Great Britain
Library of Congress Card No. applied for.
British Library Cataloguing-in-Publication Data: A catalogue record for this book is available
for the British Library
Die Deutsche Bibliothek – CIP Cataloguing-in-Publication-Data: A catalogue record for this publication
is available from Die Deutsche Bibliothek
The cover picture of a double-ladder tetraorganodistannoxane and its solid state
119
Sn NMR spectrum
was kindly provided by Jens Beckmann and Dainis Dakternieks of Deakin University.
© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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in any form – by photoprinting, microfilm, or any other means – nor transmitted or translated into a
machine language without written permission from the publishers. Registered names, trademarks, etc.
used in this book, even when not specifically marked as such, are not to be considered unprotected by
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Composition: Druckhaus »Thomas Müntzer«, 99947 Bad Langensalza
Printing: Strauss Offsetdruck GmbH, Mörlenbach
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Printed in the Federal Republic of Germany.
ISBN 3-527-31023-1
This book and the accompanging disk were carefully produced. Nevertheless, author and publisher
do not warrant the information contained therein to be free of errors. Readers are advised to keep in
mind that statements, data, illustrations, procedural details or other items may inadvertently be inac-

curate.
Preface
Organotin compounds have been claimed to have been studied by more techniques, and
to have found more applications, than the organic derivatives of any other metal. This
has resulted in an extensive literature that continues to grow at an ever-increasing rate,
and provides the justification for this second edition of Organotin Chemistry.
I have again tried to provide an analysis of and guide to that literature. Some chapters
have simply been revised and brought up to date, but most have been completely rewrit-
ten, and new sections have been added. Publications are covered up to the beginning of
2003.
This account is supplemented by the literature database on the accompanying CD,
which I hope readers will use to find their way around the organotin literature and to
counteract the severe compression and selection that is necessary in a book of this size.
Further details are given below.
I am very grateful to Peter Smith (UCL) and Fred Armitage (KCL) who read all of
the text, and to Mike Lappert, David Cardin, and Gerry Lawless (University of Sussex),
Dainis Dakternieks, Andrew Duthie, and Jens Beckmann (Deakin University), and Sarah
Wilsey (ICL) who read selected chapters. Peter Smith, Fred Armitage, and Sarah Wilsey
also helped to check the proofs. They did much to reduce the numbers of errors and
omissions, and to improve the text, but I would appreciate any comments from readers
on the book or on the database. My thanks are also due to Gudrun Walter (Wiley-VCH)
who saw the book through to publication, and to my wife for all help non-chemical.
The Organotin Database
The accompanying CD carries a database of more than 5,500 references on which this
book is based, but only a fraction of which appear in the text. It is in the form of an
EndNote

library (2Edtinlib.enl) and of a tagged text file in Refer format (2Edtinlib.txt).
Each reference carries details of the author, title, and journal, and also keywords,
usually a brief abstract, and always a note of the relevant section or sections in the book.

For example, references to papers on compounds containing a tin-silicon bond can be
retrieved by searching for the keyword SnSi or the section number 19.5.0.0. Further
details are given on the files readme.txt and keywords.txt on the CD.
The text file can be read on any word-processor and searched in the usual way, and it
can also be imported into other reference-managing programs (Refer, BibIX, ProCite,
Reference Manager, etc). The EndNote library provides more flexibility than the textfile:
the individual fields (author, title, abstract, keywords, notes etc.) can be searched and
edited, and the program also automatically compiles the bibliography of a paper. A dem-
onstration program can be downloaded from www.endnote.co.uk.
November 2003 Alwyn Davies
Chemistry Department,
University College,
20 Gordon Street,
London WC1H 0AJ, UK

Contents vii
Contents
1 Introduction 1
1.1 History 1
1.2 Nomenclature 3
1.3 Overview of Synthesis 4
1.4 Overview of Structures 6
1.5 Bibliography 8
2 Physical Methods and Physical Data 13
2.1 Physical Methods 13
2.1.1 Infrared and Raman Spectroscopy 13
2.1.2 Mössbauer Spectroscopy 14
2.1.3 Mass Spectrometry 16
2.1.4 NMR Spectroscopy 18
2.1.5 Photoelectron Spectroscopy 25

2.2 Physical Data 26
3 The Stannyl Group as a Substituent 31
3.1 Tin as a Hydrogen Equivalent 31
3.1.1 Chemical Reactions 35
3.1.2 C-Sn Hyperconjugation 36
3.1.2.1 Carbon Radicals 36
3.1.2.2 Carbon Cations: the β-Tin Effect 36
3.1.2.3 Filled π-Systems 39
3.1.2.4 Carbon Cations: the γ-, δ-, and ε-Effects 41
3.2 Stannyl Substituent Constants 41
3.2.1 Electronic Effects 41
3.2.2 Steric Effects 42
4 Formation of the Carbon-Tin Bond 45
4.1 The Reaction of Organometallic Reagents with Tin Compounds 45
4.2 The Reaction of Stannylmetallic Compounds with Organic
Electrophiles 49
4.3 The Reaction of Tin or Tin(II) Compounds with Alkyl Halides 51
4.4 The Hydrostannation of Alkenes and Alkynes 54
4.5 Metallostannation of Alkenes and Alkynes 59
4.6 The Reaction of Acidic Hydrocarbons with Sn-O and Sn-N Bonded
Compounds 60
4.7 Carbonyl-forming Eliminations 61
5 Alkylstannanes 67
5.1 Structures and Properties 67
5.2 Mechanisms of Cleavage 70
5.3 Reactions 72
5.3.1 With Protic Acids 72
viii Contents
5.3.2 With Halogens 73
5.3.3 With Lewis Acids 74

5.3.4 With Sulfur Dioxide 75
5.3.5 Tin/Lithium Transmetallation 75
5.3.6 With Free Radicals 75
5.3.7 By Electron Transfer 76
5.3.8 With Peroxides 78
5.4 Fluorous Alkylstannanes 78
6 Functionally-substituted Alkylstannanes 82
6.1 α-Halogenoalkylstannanes 82
6.2 Other α-Substituted Alkylstannanes 84
6.3 β-Functional Alkylstannanes 92
6.4 γ-Functional Alkylstannanes 94
7 Aryl- and Heteroaryl-stannanes 100
7.1 Arylstannanes 100
7.2 The Stannylium Ion and the Wheland Intermediate 105
7.3 Heteroarylstannanes 107
8 Alkenyl- and Alkynyl-stannanes, and Stannacyclopentadienes 114
8.1 Alkenyl-tin Compounds 114
8.1.1 Formation 114
8.1.2 Reactions 121
8.2 Alkynyltin Compounds 123
8.2.1 Formation 123
8.2.2 Reactions 125
8.3 Stannacyclopentadienes 128
9 Allyl-, Allenyl-, Propargyl, and Cyclopentadienyl-stannanes 133
9.1 Allylstannanes 133
9.1.1 Formation 133
9.1.2 Properties 135
9.1.3 Reactions 136
9.1.3.1 Transmetallations 136
9.1.3.2 Reaction with Electrophiles 137

9.1.3.3 Reactions with Radicals 139
9.1.3.4 Ene reactions 140
9.2 Allenyl- and Propargyl-stannanes 142
9.2.1 Preparation 142
9.2.2 Reactions 143
9.3 Cyclopentadienylstannanes 144
9.3.1 Formation 144
9.3.2 Properties 145
9.3.3 Reactions 147
9.3.4 Stannylmetallocenes 148
10 Stannacycloalkanes 156
10.1 Monostannacycloalkanes, R
2
Sn(CH
2
)
n
156
10.2 Stannacyclopentadienes 159
10.3 Oligostannacycloalkanes, [R
2
Sn(CH
2
)
n
]
m
160
Contents ix
10.3.1 Formation 160

10.3.2 Structures and Properties 162
11 Organotin Halides 166
11.1 Preparation 166
11.1.1 The Reaction of RM with SnX
4
166
11.1.2 The Kocheshkov Reaction 167
11.1.3 Preparation from Organotin Oxides or Hydroxides 168
11.1.4 Exchange of Anionic Groups at Tin 169
11.1.5 The Reactions of Halogens with Sn-Sn Bonded Compounds 170
11.2 Physical Properties and Structures 171
11.3 Coordination Complexes 174
11.4 Reactions 175
12 Organotin Hydroxides and Oxides 179
12.1 Triorganotin Hydroxides and Oxides 179
12.1.1 Preparation and Properties 179
12.1.2 Reactions 182
12.2 Diorganotin Hydroxides and Oxides 185
12.3 Monoorganotin Hydroxides and Oxides 193
12.4 Stannametalloxanes 195
13 Organotin Carboxylates and Other Oxyesters. Stannylium Ions 203
13.1 Organotin Carboxylates 203
13.1.1 Preparation 203
13.1.2 Structures 205
13.1.3 Properties 207
13.2 Carbonates and Carbamates 208
13.3 Derivatives of Phosphorus Acids 209
13.4 Organotin Derivatives of Other Oxyacids and of Thioacids 210
14 Organotin Alkoxides, Phenoxides, and Peroxides 214
14.1 Acyclic Alkoxides and Phenoxides 214

14.1.1 Preparation 214
14.1.2 Structures and Properties 218
14.1.3 Reactions 219
14.2 1,3,2-Dioxastannacycloalkanes 223
14.2.1 Formation 223
14.2.2 Structures and Properties 224
14.3 Acyclic Organotin Enolates 228
14.3.1 Preparation 229
14.3.2 Reactions 230
14.4 1,3,2-Dioxastannolenes 233
14.5 Organotin Peroxides 234
15 Organotin Hydrides 244
15.1 Preparation 244
15.1.1 Reductions with Metal Hydrides 244
15.1.2 Decarboxylation of Stannyl Formates 246
15.1.3 Hydrolysis of Stannylmetallic Compounds 247
15.1.4 Alkylation of R
2
SnHM 247
x Contents
15.1.5 Special Hydrides 248
15.2 Properties 249
15.3 Reactions 251
15.3.1 Reactions with Protic Acids and Carbenium ions. 252
15.3.2 Reactions with Metal Halides 253
15.3.3 Reactions with Strong Bases 253
15.3.4 Reactions Leading to the Formation of Sn-Sn Bonds 253
15.3.5 Radical Reactions 255
15.3.5.1 Reactions of Radicals with Tin Hydrides 256
15.3.5.2 Reduction of Halides 257

15.3.5.3 Reduction of Thiocarbonyl Compounds 259
15.3.5.4 Reduction of Other Substrates 259
16 Compounds with Sn-N Bonds 266
16.1 Aminostannanes 266
16.1.1 Preparation 266
16.1.1.1 Transmetallation 266
16.1.1.2 Transamination 267
16.1.1.3 Addition to Multiple Bonds 268
16.1.1.4 Ene Reactions 268
16.1.1.5 Miscellaneous Methods 269
16.1.2 Structures 269
16.1.3 Reactions 270
16.1.3.1 With Protic Acids 270
16.1.3.2 With Metal Derivatives 271
16.1.3.3 With Other Singly-bonded Electrophiles 272
16.1.3.4 With Doubly-bonded Electrophiles 273
16.2 Stannyl Porphyrins and Corroles 274
16.3 Amidostannanes 275
16.4 Sulfonamidostannanes 276
16.5 Stannaimines, R
2
Sn=NR′ 277
16.6 Compounds with Sn–P Bonds 278
17 Compounds with Sn-S Bonds 283
17.1 Organotin Sulfides 283
17.1.1 Preparation 283
17.1.2 Structures 285
17.1.3 Reactions 286
17.2 Stannathiones R
2

Sn=S 287
17.3 Organotin Thiolates R
n
Sn(SR′)
4-n
287
18 Compounds with Sn-Sn Bonds 292
18.1 Introduction 292
18.2 Acyclic Distannanes 292
18.2.1 Formation 292
18.2.1.1 From a Stannylmetallic Compound and a Halide R
n
SnX
4-n
292
18.2.1.2 From an Organotin Compound R
n
SnX
4-n
and a Metal 293
18.2.1.3 From an Organotin Hydride R
n
SnH
4-n
and a compound R
n
SnX
4-n
294
18.2.1.4 By Elimination of Dihydrogen from an Organotin Hydride 295

18.2.1.5 By Insertion of a Stannylene R
2
Sn: into an SnM Bond 296
18.2.1.6 By Abstraction of a Hydrogen Atom from R
3
SnH 296
Contents xi
18.2.1.7 By Cathodic Reduction of R
3
SnX 296
18.2.2 Structures 297
18.2.3 Properties 297
18.3 Linear Oligostannanes 301
18.4 Cyclic Oligostannanes 303
19 Compounds with Tin-metal Bonds 311
19.1 Alkali Metals 311
19.1.1 Formation 311
19.1.2 Properties 313
19.1.3 Structures 313
19.1.4 Reactions 314
19.1.5 Pentaorganostannates R
5
Sn
–
Li
+
315
19.2 Magnesium 316
19.3 Calcium, Strontium, and Barium 317
19.4 Boron and Aluminium 317

19.5 Silicon, Germanium, and Lead 319
19.6 Copper 321
19.7 Zinc, Cadmium, and Mercury 322
19.8 Platinum and Palladium 323
19.9 Other Transition Metals 327
20 Organotin Radicals and Radical Ions 333
20.1 Organotin Radicals R
3
Sn
•
333
20.1.1 Generation 333
20.1.2 ESR Spectra 338
20.1.3 Reactions 339
20.2 Stannylalkyl Radicals R
3
SnC
n
•
343
20.3 Radical Cations R
n
SnX
4-n
•+
344
20.4 Radical Anions R
n
SnX
4-n

•−
and R
2
Sn
•−
346
21 Stannylenes, Distannenes, and Stannenes 351
21.1 σ-Bonded Stannylenes 351
21.1.1 Transient Stannylenes 351
21.1.2 Persistent Stannylenes 353
21.2 Distannenes 359
21.3 Distannynes 360
21.4 Stannenes and Heterostannenes 361
21.5 π-Bonded Stannylenes 363
22 Organic Synthesis: Tin/Lithium Transmetallation,
the Stille Reaction, and the Removal of Tin Residues 373
22.1 Tin/Lithium Transmetallation 373
22.2 Stille Coupling Reactions 375
22.3 The Removal of Tin Residues 378
23 Applications, Environmental Issues, and Analysis 383
23.1 Applications 383
23.2 Environmental Issues 387
23.3 Analysis 388
Author Index 391
Subject Index 421
1 Introduction
1.1 History
The first organotin compound was prepared over 150 years ago. In 1849, in a paper
devoted largely to the reaction which occurred when ethyl iodide and zinc were heated
together in a sealed tube, Frankland says:

1
“In conclusion, I will describe, very briefly,
the behaviour of iodide of ethyl in contact with several other metals, at elevated tempera-
tures Tin also effected the decomposition of iodide of ethyl at about the same tempera-
ture (150 °C to 200 °C); the iodide became gradually replaced by a yellowish oily fluid,
which solidified to a crystalline mass on cooling: no gas was evolved either on opening
the tube or subsequently treating the residue with water It would be interesting to
ascertain what combination the radical ethyl enters in the last decomposition”. This
paper is often held to mark the first systematic study in organometallic chemistry.
2, 3
Et
2
SnI
2
2EtI + Sn
(1-1)
Frankland subsequently showed that the crystals were diethyltin diiodide (equation
1-1).
4–6
In independent work,
7
Löwig established that ethyl iodide reacted with a
tin/sodium alloy to give what is now recognised to be oligomeric diethyltin, which re-
acted with air to give diethyltin oxide, and with halogens to give diethyltin dihalides
(though through using incorrect atomic weights, the compositions that he ascribed to
these compounds are wrong).
As an alternative to this so-called direct method, an indirect route was devised by
Buckton in 1859,
8
who obtained tetraethyltin by treating tin tetrachloride with Frank-

land’s diethylzinc.
+ZnI
2
Et
2
Zn
2EtZnI
2EtI + 2Zn
(1-2)
Et
4
Sn + 2ZnCl
2
+SnCl
4
2Et
2
Zn
(1-3)
This direct route was developed by Letts and Collie,
9
who were attempting to prepare
diethylzinc by reaction 1–2, and instead isolated tetraethyltin which was formed from tin
which was present as an impurity in the zinc. They then showed that tetraethyltin could
be prepared by heating ethyl iodide with a mixture of zinc and tin powder.
EtI + Zn/Sn
Et
4
Sn + ZnI
2

(1-4)
The indirect route was improved by Frankland who showed that the tin(IV) tetrachlo-
ride could be replaced by tin(II) dichloride which is easier to handle and reacts in a more
controllable fashion.
Et
4
Sn + ZnCl
2
Et
2
Zn + SnC l
2
(1-5)
Up to 1900, some 37 papers were published on organotin compounds, making use of
these two basic (direct and indirect) reactions.
Organotin Chemistry, Second Edition. Alwyn G. Davies
Copyright
 2004 Wiley-VCH Verlag GmbH & Co. KGaA.
ISBN: 3-527-31023-1
2 1 Introduction
In 1900, Grignard published his synthesis of organomagnesium halides in ether solu-
tion. These reagents were much less sensitive to air than Frankland’s solvent-free or-
ganozinc compounds, and they rapidly replaced and extended the scope of the zinc re-
agents as a source of nucleophilic alkyl and aryl groups. In 1903, Pope and Peachey
described the preparation of a number of simple and mixed tetraalkylstannanes, and of
tetraphenyltin, from Grignard reagents and tin tetrachloride or alkyltin halides,
10
and
reactions of this type soon became the standard route to alkyl- and aryl-tin compounds.
This early work is summarised in Krause and von Grosse’s Organometallische Che-

mie which was published first in 1937,
11
and which described examples of tetraalkyl-
and tetraaryl-stannanes, and of the organotin halides, hydrides, carboxylates, hydroxides,
oxides, alkoxides, phenoxides, R
2
Sn(II) compounds (incorrectly), distannanes
(R
3
SnSnR
3
), and oligostannanes (R
2
Sn)
n
.
Tin played a full part in the great increase of activity in organometallic chemistry
which began in about 1949, and this was stimulated by the discovery of a variety of
applications. Structural studies have always been prominent in organotin chemistry, and
particularly the structural changes which occur between the solution and solid states.
Mössbauer spectroscopy was extensively used during the 1960s and 1970s for investi-
gating structures in the solid state, but it has now largely given place to X-ray crystallogr-
aphy and high resolution solid state tin NMR spectroscopy.
In 1962, Kuivila showed that the reaction of trialkyltin hydrides with alkyl halides
(hydrostannolysis) (equation 1-6) was a radical chain reaction involving short-lived
trialkyltin radicals, R
3
Sn•,
12
and in 1964, Neumann showed that the reaction with

non-polar alkenes and alkynes (hydrostannation) (equation 1-7) followed a similar
mechanism,
13, 14
and these reactions now provide the basis of a number of important
organic synthetic methods.
R
3
SnH + R'X
R
3
SnX + R 'H
(1-6)
R
3
SnH + C=C R
3
SnC CH
(1-7)
Salts of the free R
3
Sn
−
anion and R
3
Sn
+
cation have been examined by X-ray crystal-
lography. The formation of short-lived stannylenes, R
2
Sn:, has been established, and by

building extreme steric hindrance into the organic groups, long-lived stannylenes have
been isolated, and stable compounds with double bonds to tin, e.g. R
2
Sn=CR′
2
,
R
2
Sn=SiR′
2
, R
2
Sn=SnR′
2
, and R
2
Sn=NR′ have been prepared.
The various species of mononuclear organotin compounds with only carbon-bonded
ligands, which are known, are summarised in Table 1-1. The best evidence which is
available at the present time for the existence of these species, and the section where
they are discussed, are listed in Table 1-1.
It is convenient to denote the number of valence electrons m, and the number of
ligands n, by the notation m-Sn-n. For example the radical R
3
Sn
•
would be a 7-Sn-3
compound.
A major development in recent years has been the increasing use of organotin re-
agents and intermediates in organic synthesis, exploiting both their homolytic and het-

erolytic reactivity.
15
In parallel with these developments, organotin compounds have found a variety of
applications in industry, agriculture, and medicine, though in recent years these have
been circumscribed by environmental considerations. In industry they are used for the
stabilization of poly(vinyl chloride), the catalysis of the formation of the polyurethanes,
and the cold vulcanisation of silicone polymers, and also as transesterification catalysts.
1.2 Nomenclature 3
Table 1-1 Organotin species R
n
Sn
Formula No. of elec-
trons m
No. of
ligands n
Evidence Name Location
R
4
Sn 8 4 X-Ray stannane Chaps. 5-10
R
4
Sn
•+
7 4 ESR stannane radical cation Section 20.3
R
4
Sn
•−
9 4 ESR stannane radical anion Section 20.4
R

5
Sn
−
10 5 NMR hypervalent stannate anion Sections 5.3.5 and
22.1
R
2
Sn=CR′
2
8 3 X-Ray stannene Section 21.4
R
3
Sn
+
6 3 X-Ray stannylium ion Section 7.2
R
3
Sn
•
7 3 ESR stannyl radical Section 20.1
R
3
Sn
−
8 3 X-Ray stannate anion Section 19.1
R
2
Sn: 6 2 X-Ray stannylene Section 21.1 and 21.5
Their biological properties are made use of in antifouling paints on ships (though this is
now curtailed by legislation; see Chapter 23), in wood preservatives and as agricultural

fungicides and insecticides, and in medicine they are showing promise in cancer therapy
and in the treatment of fungal infections.
16
1.2 Nomenclature
Attempts to reconcile the practices of organic and inorganic chemists in the meeting
ground of organometallic chemistry have led to IUPAC sanctioning a number of alterna-
tive systems of nomenclature.
(1) Under the extended coordination principle, the names of the attached ligands
are given, in alphabetical order, in front of the name of the central metal; anionic
ligands are given the -o suffix. Thus Me
2
SnCl
2
would be dichlorodimethyltin, and
Me
3
SnSnMe
3
would be hexamethylditin.
(2) More commonly, the organic groups plus the metal are cited as one word, and the
anionic component(s) as another. Thus Me
2
SnCl
2
is usually called dimethyltin
dichloride, and the common (Bu
3
Sn)
2
O (tributyltin oxide or TBTO) is

bis(tributyltin) oxide.
(3) Under the substitutive scheme, monotin compounds can be named by citing re-
placement of hydrogen in the appropriate tin hydride. Stannane is SnH
4
, and
Me
2
SnCl
2
would be called dichlorodimethylstannane. The compounds Bu
3
SnSnBu
3
can similarly be called hexabutyldistannane as a derivative of distannane,
H
3
SnSnH
3
, and (Bu
3
Sn)
2
O is hexabutyl distannoxane.
(4) The organotin group can itself be treated as a substituent, the H
3
Sn group being
stannyl, and the H
2
Sn= group being stannio. This is useful in compounds with more
complicated structures, e.g. Me

3
SnCH
2
CH
2
CO
2
H is 3-(trimethylstannyl)propanoic
acid, and Et
2
Sn(C
6
H
4
OH-p)
2
is 4,4′-diethylstanniodiphenol.
(5) The suffix ‘a’ can be added to the stem of the substituent (giving stanna) and used
to indicate replacement of carbon. This is most useful with cyclic compounds, thus
cyclo-(CH
2
)
5
SnMe
2
is 1,1-dimethylstannacyclohexane. Doubly bonded compounds
are similarly named as alkenes with one or two of the doubly-bonded atoms replaced
by tin: the compound R
2
Sn=CR

2
is a stannene, and R
2
Sn=SnR
2
is a distannene.
(6) By analogy with alkyl radicals and carbenes (methylenes), the species R
3
Sn
•
are
stannyl radicals, and the species R
2
Sn: are stannylenes or stannyldiyls.
4 1 Introduction
Chemical Abstracts indexing practice is summarised in the 1992 Index Guide, page
199, and is as follows.
(1) Acyclic compounds are named as derivatives of the acyclic hydrocarbon parents (see
item 3 above), with an “ane” modification to indicate the presence of a chalcogen,
for example H
4
Sn, stannane; H
3
Sn(SnH
2
)
11
SnH
3
, tridecastannane; (H

3
SnO)
2
SnH
2
,
tristannoxane.
(2) Heterocyclic compounds are named as stanna replacement of carbon (see item 5
above).
(3) As substituent prefixes, H
3
Sn- is indicated by stannyl, H
2
Sn= by stannylene, and
HSn≡ by stannylidyne.
Some illustrative examples are as follows.
Bu
2
SnO stannane, dibutyloxo
Bu
2
Sn
2+
stannanediylium, dibutyl
Me
3
SnCN stannacarbonitrile, trimethyltin cyanide
ClSnMe
2
OSnMe

2
Cl distannoxane, 1,3-dichloro-1,1,3,3,-tetramethyl
Me
3
SnCH=CHCH=CHSnMe
3
stannane, 1,3-butadiene-1,4-diylbis[trimethyl
cyclo-BrPhSn(CH
2
)
6
SnBrPh(CH
2
)
6
-, 1,8-distannacyclotetradecane, 1,8-dibromo-1,8-di-
phenyl.
If there is doubt, the correct name can usually be found through the formula index.
1.3 Overview of Synthesis
An overview of the principal groups of organotin compounds and their interconversions
is given in Scheme 1-1, which deals mainly with tin(IV) compounds, and Schemes 1-2
and 1-3 which cover compounds related to tin(III) and tin(II) species, respectively. It
RX
SnX
2
Sn
RI
_
X
R

2
SnX
2
L
_
_
_
_
_
_
HO
HO
HO
X
X
X
L
L
base
LiAlH
4
LiAlH
4
200
o
C
SnCl
4
RMgX
R

2
SnXCl
(R
2
SnO)
n
ClR
2
SnOSnR
2
Cl
R
2
SnCl
2
L
2
R
2
SnH
2
R
2
SnCl
2
(X = OR', NR
2
', SR', OCOR', etc)
R
3

SnX
R
3
SnOSnR
3
R
3
SnOH
RSn(OH)Cl
2
[RSn(O)OH]
n
RSnCl
3
RSnCl
3
L
2
(R
2
Sn)
n
R
3
SnSnR
3
R
3
SnClL
R

3
SnH
R
4
Sn
RSnX
3
R
3
SnCl
SnCl
4
Scheme 1-1 Organotin synthesis based on the Grignard and Kocheshkov reactions.
1.3 Overview of Synthesis 5
R
3
SnCl
R
3
SnH
R
3
SnSnR
3
R
3
SnM
LiAlH
4
M

Pd
o
R
3
SnCl
hν
R
3
Sn
CC
CC
CCHR
3
Sn
CC
R
3
Sn
H
R'X
R
3
SnR'
Scheme 1-2 Organotin synthesis based on reactions of SnH and SnM compounds.
R*
2
SnCl
2
Cp
2

Sn:
R
2
Sn:
Cp
2
SnX
2
CpSnX
R'Cp
2
SnX
R
2
Sn
R'
R'
R*
2
Sn SnR*
2
N
SnR*
2
R*
2
Sn
Mes
MesN
3

CpNa
RLi
RLi
R'X
X
2
HX
R'R'
R*
2
Sn SnR*
2
Sn
(R
2
Sn)
n
Scheme 1-3 Routes to lower valence state organotin compounds.
should be emphasised that, particularly with respect to Scheme 1-3, some of the reac-
tions shown are as yet known only for specific organotin compounds, and are not neces-
sarily general reactions.
Products which result from the formation of a new tin-carbon bond are boxed in the
Schemes. The four principal ways in which this can be accomplished are the reaction of
metallic tin or a tin(II) compound with an organic halide, of an organometallic reagent
RM (M = lithium, magnesium, or aluminium) with a tin(II) or tin(IV) halide, of a trial-
kyltin hydride with an alkene or alkyne, or of a triorganotin-lithium reagent (R
3
SnLi)
with an alkyl halide.
The reaction which is most commonly used is that of a Grignard reagent with tin

tetrachloride; complete reaction usually occurs to give the tetraorganotin compound
(Scheme 1-1). This is then heated with tin tetrachloride when redistribution of the groups
R and Cl occurs to give the organotin chlorides, R
n
SnCl
4-n
(n = 3, 2, or 1) (the Kochesh-
kov comproportionation). Replacement of the groups Cl with the appropriate nucleophile
X (HO
–
, RCO
2
–
, RO
–
etc.) then occurs readily to give the derivatives R
n
SnX
4–n
.
6 1 Introduction
With a metal hydride as the nucleophile, the organotin hydrides, R
n
SnH
4-n
are
formed, which, by addition to an alkene or alkyne (hydrostannation), usually by a radical
chain mechanism involving stannyl radicals, R
3
Sn

•
, provide the second way of generat-
ing the tin-carbon bond (Scheme 1-2).
Under the influence of a base or a platinum catalyst, the triorganotin hydrides and
dialkyltin dihydrides eliminate hydrogen to give the distannanes (R
3
SnSnR
3
) and the
oligostannanes (R
2
Sn)
n
, respectively. The halides, hydrides, or distannanes can be con-
verted into the metallic derivatives R
3
SnM, where M is an alkali metal, and these act as
sources of nucleophilic tin, which, by reaction with alkyl halides, provide a further way
of creating a tin-carbon bond.
Recent years have seen important developments in the chemistry of tin(II) com-
pounds and compounds with multiple bonds to tin (Scheme 1-3). The cyclopentadi-
enyltin(II) compounds, which are formed from CpM and SnCl
2
, are pentahapto mono-
mers. When R is a simple alkyl or aryl group, the stannylenes R
2
Sn(II) are known only
as short-lived reactive intermediates, but when the organic group is bulky [e.g.
bis(trimethylsilyl)methyl or 2,4,6-trisubstituted aryl], as indicated by R* in Scheme 1-3,
the monomeric stannylenes, R*

2
Sn:, have been isolated, and have provided routes to the
stannenes (R*
2
Sn=CR
2
) and distannenes (R*
2
Sn=SnR*
2
), and other compounds with a
multiple bond to tin.
1.4 Overview of Structures
This description of the various types of organotin compounds must be supplemented by
a description of the structures of the compounds, which are seldom as simple as the
above formulae might indicate, and which frequently depend on the physical state of the
sample.
Simple tetraalkyl- and tetraaryl-tin(IV) compounds exist under all conditions as tetra-
hedral monomers, but in derivatives R
n
SnX
4–n
(n = 1 to 3), where X is an electronegative
group (halide, carboxylate etc.), the Lewis acid strength of the tin is increased, and
Lewis bases form complexes with a higher coordination number. The compounds
R
3
SnX usually give five-coordinate complexes R
3
SnXL which are approximately trigo-

nal bipyramidal, and the compounds R
2
SnX
2
and RSnX
3
usually form six-coordinate
complexes R
2
SnX
2
L
2
and RSnX
3
L
2
which are approximately octahedral. The first such
complex to have its structure determined by X-ray crystallography was Me
3
SnCl,py
(1-1) and some further examples of such complexes are shown in structures 1-2 and
1-3.
Sn
Me
Me
Me
N
Cl
N

N
Sn
Cl
Cl
Bu
Bu
Cl
Bu
Sn Cl
Cl
Cl
Cl
2-
(1-1) (1-2) (1-3)
The groups X, however, usually carry unshared electron pairs, and can themselves act
as Lewis bases, resulting in intermolecular self-association to give dimers, oligomers, or
polymers. Some examples are shown in formulae 1-4 –1-6.
1.4 Overview of Structures 7
Sn
F
Sn
F
Me
Me
Me
Me
F
F
F
F

Sn
F
Sn
F
Me
Me
Me
Me
F
F
O
Sn
O
O
Sn
O
Bu
2
t
Bu
2
t
CN
Me
Me
CN
Sn
Me
(1-4) (1-5) (1-6)
This self-association is governed by the nature of the ligands L and also by the steric

demands of R, X, and L, and it is common for the degree of association to increase in the
sequence gas < solution < solid.
If R or X carries a functional substituent Y beyond the α-position, the alternative of
intramolecular coordination can occur leading to the formation of monomers with 5-, 6-,
7-, or 8-coordinated tin. Some examples are shown in formulae 1-7 –1-10.
C
S
S
Et
2
N
C
S
S
NEt
2
Sn
Ph
S
S
C
NEt
2
N
Sn
Me
Sn
NM e
2
NM e

2
C
6
H
4
Me
I
I
Cl
OMe
O
Cl
O
Sn
OMe
(1-7) (1-8) (1-9) (1-10)
The structures of these intramolecularly self-associated monomers, oligomers, and
polymers are seldom those of regular polyhedra, and the determination of their struc-
tures, and the steric and electronic factors which govern them, has been an important
feature of organotin chemistry since the early 1960s. Initially the evidence came largely
from proton NMR spectra and IR spectra on solutions, and IR and Mössbauer spectra on
the solid state, supported by a few X-ray studies of single crystals.
17–19
More recently,
comparison of the high resolution
119
Sn (or
117
Sn) NMR spectra in solution and the solid
state has proved to be a very sensitive indicator of changes in structure, and single crys-

tal X-ray studies are now commonplace.
20–22
Systematic studies of organotin(II) compounds (Chapter 21) are much less extensive
than those of tin(IV) compounds, but already it is apparent that there is a wide variety of
structures. In bis(cyclopentadienyl)tin(II), the two rings are pentahapto-bonded, but the
lone pair is stereochemically active and the rings are non-parallel. Other cyclopentadi-
enyltin compounds, however, are known in which the rings are parallel, or the hapticity
may change, or the CpSn
+
ion may be present. The discovery of the σ-bonded stannylene
[(Me
3
Si)
2
CH]
2
Sn(II) (Lappert’s stannylene) in 1973 has stimulated a lot of studies. In
the vapor phase it is monomeric, but in the solid state a dimer of C
2h
symmetry is
formed. Many further diarylstannylenes, Ar
2
Sn(II), and their corresponding distannenes,
Ar
2
Sn=SnAr
2
, with sterically hindering ortho substitutents have subsequently been pre-
pared.
No Sn(III) radicals have yet been isolated (Chapter 20), though some are known

which are stable in solution, in equilibrium with their dimers. Evidence regarding their
structures comes mainly from ESR spectroscopy, which shows that, in contrast to car-
bon-centred radicals which are planar, tin-centred radicals are pyramidal even when the
tin carries aryl ligands.
These topics are dealt with in detail in subsequent chapters.
8 1 Introduction
1.5 Bibliography
This section lists, largely chronologically, the more important general reviews of organo-
tin chemistry, with some comments as to their contents. More specialised reviews are
referred to at the appropriate sections in the text. Extensive bibliographies are also given
in the volume of Houben Weyl, in volumes 1, 5, 8, 9, 11, 14, 16, 17, 18, 19, and 20 of
Gmelin, and in Science of Synthesis, which are referred to below.
The Chemical Review by Ingham, Rosenberg, and Gilman (1960),
23
and the three
volumes of Organotin Chemistry edited by Sawyer (1971),
24
provide an extensive if not
comprehensive listing of the organotin compounds which were known at those dates.
Reprints of the Chemical Review were widely circulated and did much to stimulate inter-
est in the subject. The various volumes of Gmelin give a thorough coverage of the com-
pounds known at the date the material went to press; thereafter, one is dependent on
Chemical Abstracts.
E. Krause and A. von Grosse, Die Chemie der Metal-organischen Verbindungen,
(1937, reprinted 1965). Pages 311-372 relate to organotin chemistry.
11
M. Dub, Organometallic Compounds, Literature Survey, 1937-1959, Vol. II Organic
Compounds of Germanium, Tin, and Lead (1961).
25
A non-critical compendium listing

preparations and physical and chemical properties, compiled from Chemical Abstracts.
Pages 79-253 relate to organotin chemistry. This supplements the data given in Krause
and von Grosse’s book.
W.P. Neumann Die Organische Chemie des Zinns, (1967),
26
and its revised and
translated edition: W.P. Neumann The Organic Chemistry of Tin, (1970).
19
K.A. Kocheshkov, N.N. Zemlyanskii, N.I. Sheverdina, and E.M. Panov,MetodiEle-
mento-organicheskoi Khimii. Germanii, Olovo, Svinesh, (1968).
27
Pages 162-530 give a
thorough coverage of organotin chemistry, though in Russian.
R.C. Poller, The Chemistry of Organotin Compounds, 1970.
18
Organotin Compounds, ed. A.K. Sawyer, (1971), vols. 1, 2, 3. Comprehensive
coverage in fourteen chapters by a variety of authors, with extensive lists of compounds;
written at a time before organotin compounds were used extensively in organic synthe-
sis.
24
P.J. Smith, A Bibliography of X-ray Crystal Structures of Organotin Compounds
(1981).
28
B.J. Aylett. Organometallic compounds, 4th. Edn. Vol. 1 The Main Group Ele-
ments, Part 2. Groups IV and V. (1979).
29
Pages 177-276 deal with organotin chemis-
try.
Organotin Compounds: New Chemistry and Applications, ed. J.J. Zuckermann
(1976).

30
Based on lectures given at the centenary meeting of the ACS.
G. Bähr and S. Pawlenko, in Methoden der Organischen Chemie (Houben Weyl),
vol. 13/6, (1978), pp. 181-251.
31
Emphasises preparative methods, with brief experimen-
tal details.
A.G. Davies and P.J. Smith, Adv. Inorg. Chem. Radiochem., 1980, 23, 1.
32
A.G. Davies and P.J. Smith, Tin in Comprehensive Organometallic Chemistry,
(1982); reprints of this were widely circulated.
33
M. Pereyre, J P. Quintard and A. Rahm, Tin in Organic Synthesis, (1987). Still the
only book on this increasingly important aspect of organotin chemistry, though there is
an excellent supplement in the 2nd edition of Chemistry of Tin (1998), which is noted
below.
Organotin Compounds in Organic Synthesis, Tetrahedron Symposia in Print No. 36,
Ed. Y. Yamamoto (1989).
34
References to Chapter 1 9
Organometallic Synthesis, ed. J.J. Eisch and R.B. King, Vol. 2, 1981;
35
Vol. 3,
1986;
36
Vol. 4, 1988.
37
Give tested experimental details for the synthesis of some 40
organotin compounds.
Chemistry of Tin, ed. P.G. Harrison, (1989).

38
Covers both inorganic and organic
aspects. Chapters on organotin chemistry are as follows. General trends (P.G. Harrison).
Spectroscopy (P.G. Harrison). Formation of the tin-carbon bond (J.L. Wardell). Organic
compounds of Sn(IV) (K.C. Molloy). Organic compounds of Sn(II) (P.D. Lickiss).
Tin-metal bonded compounds (F. Glockling). Radical chemistry of tin (A.G. Davies).
Organotin compounds in organic synthesis (J.L. Wardell). Biological chemistry of tin
(M.J. Selwyn). Industrial uses (C.J. Evans).
I. Omae, Organotin Chemistry, (1989), 355 pages. A then up-to-date survey of the
field.
39
E. Lukevics and L. Ignatovics, Frontiers of Organogermanium, -Tin and -Lead
Chemistry (1993).
40
Accounts of the plenary lectures given at a meeting in Riga in 1992.
References to specific chapters are given elsewhere in this book.
H. Nozaki, Organotin Chemistry in Organometallics in Synthesis Ed. M. Schlosser,
(1994).
41
Volume 2 (2002) contains articles on organotin chemistry by J.A. Marshall,
and on the Stille reaction by L.S. Hegedus.
A.G. Davies, Tin in Comprehensive Organometallic Chemistry, II, ed. E.W. Abel,
F.G.A. Stone and G. Wilkinson, (1995).
42
This covers the period 1982–1992.
T. Sato, Main-group Metal Organometallics in Organic Synthesis: Tin in Compre-
hensive Organometallic Chemistry II, ed. E.W. Abel, F.G.A. Stone, and G. Wilkinson,
(1995), Vol. 11, pp. 356–387.
43
Dictionary of Organometallic Compounds, Chapman and Hall, London, second edi-

tion, 1995.
44
Preparative procedures and properties, with leading references, are given
for 970 important organotin compounds.
H. Ali and J.E. van Lier, Synthesis of Radiopharmaceuticals via Organotin Interme-
diates.
45
Organotin compounds react rapidly and chemo-, regio-, and stereo-selectively
with a variety of reagents, and this has been exploited in the synthesis of pharma-
ceuticals with a radioactive label, particularly when the radioisotope has a short half-
life. A second review covering similar ground is included in Patai’s volume, as noted
below.
M.I. Bruce, Structures of Organometallic Compounds Determined by Diffraction
Methods, in Comprehensive Organometallic Chemistry II, ed. E.W. Abel, F.G.A. Stone,
and G. Wilkinson, (1995), vol. 13.
46
Pages 1107-1149 give a comprehensive listing of
organotin compounds (ca. 1500 entries) which have had their structure determined by
electron diffraction or X-ray diffraction.
The Chemistry of Organic Germanium, Tin and Lead Compounds ed. S. Patai,
(1995).
47
Many of the articles emphasise the comparison between the three
metals. Chapters which cover tin are as follows. The nature of the C-M bond (H. Basch
and T. Hoz). Structural aspects (K.M. Mackay). Stereochemistry and conformation
(J.A. Marshall and J.A. Jablonowski), Thermochemistry (J.A.M. Simões, J.F. Lieb-
man, and S.W. Slayden). ESR spectra (J. Iley). PES (C. Cauletti and S. Stranges). Ana-
lytical aspects (J. Zabicky and S. Grinberg). Synthesis of M(IV) organome-
tallic compounds (M = Ge, Sn, Pb) (J.M. Tsangaris, R. Willem and M. Gielen). Aci-
dity, complexing, basicity and H-bonding (A. Schulz and T.A. Klapötke). Substituent

effects of Ge, Sn and Pb groups (M. Charton). Electrochemistry (M. Michman). Photo-
chemistry (C.M. Gordon and C Long). Isotopically labelled organic derivatives
(K.C. Westway and H. Joly). Environmental methylation (P.J. Craig and J.T. van El-
teren). Organotin toxicology (L.R. Sherman). Safety and environmental effects
(S. Maeda).
10 1 Introduction
Tributyltin: Case Study of an Environmental Contaminant, ed. S.J. de Mora, (1996).
48
Chapters by various authors cover the different aspects of the problems associated with
the use of tributyltin compounds in marine antifouling paints.
A.G. Davies, Organotin Chemistry, 1997. The first edition of this book.
49
Chemistry of Tin, Second Edition, ed. P.J. Smith, (1998).
50
This second edition con-
tains the following chapters on organotin compounds. General trends (P.G. Harrison).
Formation and cleavage of the tin-carbon bond (J.L. Wardell). Organometallic com-
pounds of tetravalent tin (K.C. Molloy). Organometallic compounds of bivalent tin (P.D.
Lickiss). Tin-metal bonded compounds (F. Glockling). Radical chemistry of tin (A.G.
Davies). The uses of organotin compounds in organic synthesis (B. Jousseaume and
M. Pereyre). Recent studies on the mode of biological action of di- and trialkyltin com-
pounds (Y. Arakawa). Health and safety aspects of tin chemicals (P.J. Smith). Industrial
uses of organotin compounds (C.J. Evans). Solid state NMR spectroscopy of tin com-
pounds (T.N. Mitchell).
119m
Sn Mössbauer studies on tin compounds (R. Barbieri,
F. Huber, L. Pellerito, G. Ruissi, and A. Silvestri). The analysis of organotin compounds
from the natural environment (D.P. Miller and P.J. Craig).
I. Omae, Applications of Organometallic Compounds, (1998).
51

Gmelin Handbuch der Anorganischen Chemie, Tin.
52
Part 1: Tin Tetraorganyls SnR
4
(1975). Part 2: Tin Tetraorganyls R
3
SnR′ (1975). Part 3: Tin Tetraorganyls R
2
SnR′
2
,
R
2
SnR′R, RR′SnRR′, Heterocyclics and Spiranes (1976). Part 4: Organotin Hydrides
(1976). Part 5: Organotin Fluorides. Triorganotin Chlorides (1978). Part 6: Diorganotin
Dichlorides. Organotin Trichlorides (1979). Part 7: Organotin Bromides (1980). Part 8:
Organotin Iodides, Organotin Pseudohalides (1981). Part 9: Triorganotin Sulphur
Compounds (1982). Part 10: Mono- and Diorganotin Sulphur Compounds. Organo-
tin-Selenium and Tellurium Compounds (1983). Part 11: Trimethyltin- and Triethyl-
tin-Oxygen Compounds (1984). Part 12: Tripropyltin- and Tributyltin-Oxygen Com-
pounds (1985). Part 13: Other R
3
Sn-Oxygen Compounds. R
2
R′Sn- and RR′RSn-Oxygen
Compounds (1986). Part 14: Dimethyltin-, Diethyltin-, and Dipropyltin-Oxygen Com-
pounds (1986). Part 15: Di-n-butyltin-Oxygen Compounds (1988). Part 16: Diorgany-
tin-Oxygen Compounds with R
2
Sn, RR′Sn, or Cyclo(RSn) Units and with Identical or

Different Oxygen-Bonded Groups (1988). Part 17: Organotin-Oxygen Compounds of the
Types RSn(OR′)
3
, RSn(OR′)
2
OR; R
2
Sn(X)OR′, RSnX(OR′)
2
and RSnX
2
(OR′) (1989).
Part 18: Organotin-Nitrogen Compounds. R
3
Sn-N Compounds with R = Methyl, Ethyl,
Propyl, and Butyl (1990). Part 19: Organotin-Nitrogen Compounds (concluded). Or-
ganotin-Phosphorus, -Arsenic, -Antimony, and -Bismuth Compounds (1991). Part 20:
Compounds with Bonds Between Tin and Main Group IV to Main Group I–IV Ele-
ments (1993). Part 21: Compounds with Bonds Between Tin and Transition Metals of
Groups III to IV (1994). Part 22: Compounds with Bonds Between Tin and Transition
Metals of Groups VIII, I, and II (1995). Part 23. Tin-centred radicals, tin(II) compounds,
compounds with tin-element double bonds, tin(II) complexes with aromatic systems,
stannacarboranes, and other organotin compounds (1995).
All these have been collated by Herbert and Ingeborg Schumann. The Gmelin
handbooks cover comprehensively the organometallic compounds of tin. They are
available in rather few libraries, but the database can be accessed and searched by computer.
C.E. Holloway and M. Melnik, Tin Organometallic Compounds: Classification and
Analysis of Crystallographic and Structural Data. Part I. Monomeric Derivatives
(2000).
53

C.E. Holloway and M. Melnik, Part II. Dimeric derivatives. (2000).
54
C.E.
Holloway and M. Melnik. Part III. Oligomeric derivatives (2000).
55
C.E. Holloway and
M. Melnik, Heterometallic tin compounds: Classification and Analysis of Crystallo-
graphic and Structural Data: Part I. Dimeric Derivatives (2001).
56
Science of Synthesis, Vol. 5, (2003).
57
See the textfile on the CD. This is the succes-
sor to Houben Weyl.
References to Chapter 1 11
References to Chapter 1
1.1 E. Frankland, J. Chem. Soc., 1849, 2, 263.
1.2 E. G. Rochow, J. Chem. Educ., 1966, 43, 58.
1.3 J. W. Nicholson, J. Chem. Educ., 1989, 66, 621.
1.4 E. Frankland, Phil. Trans., 1852, 142, 417.
1.5 E. Frankland, Liebigs Ann. Chem., 1853, 85, 329.
1.6 E. Frankland, J. Chem. Soc., 1854, 6, 57.
1.7 C. Löwig, Liebigs Ann. Chem., 1852, 84, 308.
1.8 G. B. Buckton, Phil. Trans., 1859, 149, 417.
1.9 E. A. Letts and J. N. Collie, Phil. Mag., 1886, 22, 41.
1.10 W. J. Pope and S. J. Peachey, Proc. Chem. Soc., 1903, 19, 290.
1.11 E. Krause and A. von Grosse, Die Chemie der Metal-organischen Verbindun-
gen, Borntraeger, Berlin, 1937.
1.12 H. G. Kuivila, L. W. Menapace, and C. R. Warner, J. Am. Chem. Soc., 1962, 84,
3584.
1.13 W. P. Neumann and R. Sommer, Liebigs Ann. Chem., 1964, 675, 10.

1.14 H. G. Kuivila, Adv. Organomet. Chem., 1964, 1, 47.
1.15 M. Pereyre, J. P. Quintard, and A. Rahm, Tin in Organic Synthesis, Butterworth,
London, 1987.
1.16 C. J. Evans and S. Karpel, Organotin Compounds in Modern Technology, El-
sevier, Amsterdam, 1985.
1.17 R. C. Poller, J. Organomet. Chem., 1965, 3, 321.
1.18 R. C. Poller, The Chemistry of Organotin Compounds, Logos Press, London,
1970.
1.19 W. P. Neumann, The Organic Chemistry of Tin, Wiley, London, 1970.
1.20 J. A. Zubieta and J. J. Zuckerman, Prog.Inorg.Chem., 1978, 24, 251.
1.21 P. J. Smith, J. Organomet. Chem. Library, 1991, 12, 97.
1.22 J. T. B. H. Jastrzebski and G. van Koten, Adv. Organomet. Chem., 1993, 34,
242.
1.23 R. K. Ingham, S. D. Rosenberg, and H. Gilman, Chem. Rev., 1960, 60, 459.
1.24 A. K. Sawyer (Ed.) Organotin Compounds, Marcel Dekker, New York, 1971.
1.25 M. Dub, Organometallic Compounds, Literature Survey 1937-1959. Vol. II. Or-
ganic Compounds of Germanium, Tin, and Lead., Springer Verlag, Berlin, 1961.
1.26 W. P. Neumann, Die Organische Chemie des Zinns, Ferdinand Enke Verlag,
Stuttgart, 1967.
1.27 K. A. Kocheshkov, N. N. Zemlyansky, N. I. Sherevdina, and E. M. Panov, Me-
todi Elemento-organicheskoi Khimii. Germanii, Olovo, Svine, Nauka, Moscow,
1968.
1.28 P. J. Smith, J. Organomet. Chem. Library, 1981, 12, 97.
1.29 B. J. Aylett, Organometallic Compounds. 4th. Edn. Vol. 1. The Main Group
Elements, Part 2. Groups IV and V., Chapman and Hall, London, 1979.
1.30 J. J. Zuckerman (Ed.) Organotin Compounds: New Chemistry and Applications,
American Chemical Society, Washington, 1976.
1.31 G. Bähr and S. Pawlenko, in Houben Weyl, Methoden der Organische Chemie,
vol. 13/16, Vol. 13/6,, Thieme, Stuttgart, 1978.
1.32 A. G. Davies and P. J. Smith, Adv. Inorg. Chem. Radiochem., 1980, 23, 1.

1.33 A. G. Davies and P. J. Smith, in Comprehensive Organometallic Chemistry,
Vol. 2, G. Wilkinson, F. G. A. Stone, and E. W. Abel (Eds.), Pergamon Press,
Oxford, 1982.
12 1 Introduction
1.34 Y. Yamamoto, Tetrahedron , Symposia in Print No 36., 1989, 45, 909.
1.35 R. B. King and J. J. Eisch (Eds.) Organometallic Syntheses, Vol 2, Academic
Press, New York, 1981.
1.36 R. B. King and J. J. Eisch (Eds.), Organometallic Syntheses Vol. 3, Elsevier,
Amsterdam, 1986.
1.37 R. B. King and J. J. Eisch (Eds.), Organometallic Syntheses Vol. 4, Elsevier,
Amsterdam, 1988.
1.38 P. G. Harrison (Ed.) Chemistry of Tin, Blackie, Glasgow, 1989.
1.39 I. Omae, Organotin Chemistry (J. Organomet. Chem. Library, vol 21), Elsevier,
Amsterdam, 1989.
1.40 E. Lukevics and L. Ignatovich (Eds.), Frontiers of Organogermanium, Tin and
Lead Chemistry., Latvian Institute of Organic Synthesis, Riga, 1993.
1.41 H. Nozaki, in Organometallics in Synthesis, M. Schlosser (Ed.), Wiley, Chi-
chester, 1994.
1.42 A. G. Davies, in Comprehensive Organometallic Chemistry, Vol. 2, E. W. Abel,
F. G. A. Stone, and G. Wilkinson (Eds.), Pergamon, Oxford, 1995.
1.43 T. Sato, in Comprehensive Organometallic Chemistry II., Vol. 11, E. W. Abel,
F. G. A. Stone, and G. Wilkinson (Eds.), Pergamon, Oxford, 1995.
1.44 P. G. Harrison, in Dictionary of Organometallic Compounds. Second edition, J.
Macintyre (Ed.), Chapman and Hall, London, 1995.
1.45 H. Ali and J. E. van Lier, Synthesis, 1996, 423.
1.46 M. I. Bruce, in Comprehensive Organometallic Chemistry II, Vol. 13, E. W.
Abel, F. G. A. Stone, and G. Wilkinson (Eds.), Pergamon, Oxford, 1995.
1.47 S. Patai (Ed.) The Chemistry of Organic Germanium, Tin and Lead Compounds,
Wiley, Chichester, 1995.
1.48 S. J. de Mora (Ed.) Tributyltin: Case Study of an Environmental Contaminant,

Cambridge University Press, Cambridge, 1996.
1.49 A. G. Davies, Organotin Chemistry, VCH, Weinheim, 1997.
1.50 P. J. Smith (Ed.) Chemistry of Tin, 2nd. edn., Blackie, London, 1998.
1.51 I. Omae, Applications of Organometallic Compounds., Wiley, Chichester, 1998.
1.52 H. Schumann and I. Schumann, Gmelin Handbuch der Anorganischen Chemie:
Tin, Parts 1–14, Springer, Berlin, 1975–1996.
1.53 C. E. Holloway and M. Melnik, Main Group Metal Chem., 2000, 23, 1.
1.54 C. E. Holloway and M. Melnik, Main Group Metal Chem., 2000, 23, 331.
1.55 C. E. Holloway and M. Melnik, Main Group Metal Chem., 2000, 23, 555.
1.56 C. E. Holloway and M. Melnik, Main Group Metal Chem., 2001, 24, 133.
1.57 E.J. Thomas, in Science of Synthesis, Vol. 5. Compounds of Group 14 (GE, Sn,
Pb), M. G. Maloney (Ed.), Thieme, Stuttgart, 2003.
2 Physical Methods and Physical Data
2.1 Physical Methods
The remark has been made that compounds of tin can be studied by more techniques
than those of any other element. The fact that it has more stable isotopes that any other
element gives it very characteristic mass spectra, and isotopic labelling can be used to
interpret vibrational spectra, and for spiking samples in trace analysis; two of the iso-
topes have spin 1/2 and are suitable for NMR spectroscopy, and their presence adds
information to the ESR spectra of radical species. Further, the radioactive isotope
119m
Sn
is appropriate for Mössbauer spectroscopy. The structural complications that are referred
to in the previous chapter have therefore been investigated very thoroughly by spectro-
scopic and diffraction methods, and structural studies have always been prominent in
organotin chemistry.
In the sections that follow, the basic theory of these techniques will be discussed only
insofar as it is specially relevant to organotin compounds. It must always be borne in
mind that the structures of organotin compounds which carry functional groups may be
dependent on the physical state (gaseous, solid, or liquid), and, when the compounds are

in solution, on the nature of the solvent and on the concentration. For example, the
Sn–Cl stretching frequency in the far IR spectra of trimethyltin chloride in solution can
be correlated with the donor number of the solvent. Caution must therefore always be
exercised in attempting to quote “typical” values for properties such as vibrational fre-
quences or NMR chemical shifts.
2.1.1 Infrared and Raman Spectroscopy
1–3
Typical vibrational frequencies for organotin compounds are tabulated by Neumann,
4
Poller,
5
Omae,
6
Harrison,
2
and Nakamoto
3
and data on individual compounds can be
found in the relevant volumes of Gmelin.
7
Tetraorganotin compounds, R
4
Sn, show little tendency to be other than tetrahedrally
4-coordinate, and their vibrational frequencies are not dependent on the physical state
(Table 2-1). The force constants in Me
4
Sn are fSn–C 2.19, and fC–H 4.77 N cm
–1
.
8

The
CF
3
–Sn bond is longer and weaker than the CH
3
–Sn bond [220.1(5) pm in (CF
3
)
4
Sn and
Table 2-1 Sn–C And C≅C vibrational frequencies (cm
–1
) in tetraorganostannanes.
Compound ν
as
SnC ν
s
SnC δCSnC νC≅C
Me
4
Sn 529 508 157
Et
4
Sn 508 490 132, 86
(CF
3
)
4
Sn 211
(CH

2
=CH)
4
Sn 531 490 1583
(HC≡C)
4
Sn 504 447 2043
(CH
2
=CHCH
2
)
4
Sn 487 474 1624
(CH
2
=CHCH
2
)
2
SnMe
2
454 2016
Ph
4
Sn 268, 263 221
Organotin Chemistry, Second Edition. Alwyn G. Davies
Copyright
 2004 Wiley-VCH Verlag GmbH & Co. KGaA.
ISBN: 3-527-31023-1

14 2 Physical Methods and Physical Data
214.3(3) pm in (CH
3
)
4
Sn], and the force constant is reduced to 1.86 N cm
–1
.
9
Isotopic
labelling with
116
Sn and
124
Sn in Ph
4
Sn has been used to identify ν
as
SnC at 268 and 263
respectively, and ν
s
SnC 221 cm
-1
.
10
Organotin hydrides, R
n
SnH
4-n
, are also tetrahedral monomers under normal condi-

tions. Me
3
SnH Shows ν(SnH) 1834 cm
–1
, δ(SnH) 545 cm
–1
, and in Me
3
SnD, ν(SnD) is
1337 cm
–1
. The value of ν(SnH) varies from about 1780 cm
–1
(in Cy
3
SnH) to 1910 cm
–1
(in Vin
3
SnH), but it is always strong and convenient for monitoring reactions by IR
spectroscopy.
The third class of compounds that are not prone to increase their coordination num-
bers are the hexaalkyldistannanes, R
3
SnSnR
3
, and the related oligostannanes. The Sn–Sn
stretch is infrared inactive, but Raman active, and Me
3
SnSnMe

3
shows ν(SnSn)
192 cm
–1
. If the phenyl groups in hexaphenylditin are alkylated in the ortho positions,
steric hindrance weakens the Sn–Sn bond, and the vibration frequency and force con-
stant are reduced (see Table 18-2).
In many types of triorganotin compounds, R
3
SnX, self association to give an oli-
gomer (–R
3
SnX–)
n
places the two groups X in the axial position, and the three groups R
coplanar in the equatorial position, in a trigonal bipyramidal arrangement about tin. The
symmetrical vibration of the R
3
Sn moiety is therefore rendered infrared inactive (though
it remains Raman active) and the absence of the ν
s
band in the IR spectrum at ca.
510 cm
–1
was used a lot in the early days of organotin structural chemistry as evidence
for the oligomerisation.
5
Similarly the presence of two Sn–O stretching frequencies at
ca. 1570 and 1410 cm
–1

in solid and molten trialkyltin carboxylates shows that the CO
2
group has C
2v
symmetry with equivalent C– O bonds, confirming the oligomeric structure
(–SnR
3
–O–CR=O–)
n
.
Vibrational frequencies which have been assigned to SnX bonds in compounds of
known structure are given in Table 2-2.
Table 2-2 Vibrational frequencies of Sn – X bonds.
Compound νSnX/cm
–1
Compound νSnX/cm
–1
R
3
SnH 1777 –1846 R
3
SnNR
2
520–620
R
2
SnH
2
1820 – 1863
RSnH

3
1855 – 1880 R
3
SnSR′ 320 – 370
R
3
SnF 340–377 Me
3
SnSnMe
3
192
R
3
SnCl 318–336 Ph
3
SnSnPh
3
138
R
3
SnBr 222–234 (Me
3
Sn)
4
Sn 159, 198
R
3
SnI 176 – 204
Me
3

SnCl
2
–
227
Me
3
SnBr
2
–
140 (2,4,6-Et
3
C
6
H
2
)
6
Sn
2
92
Me
3
SnI
2
–
134
Me
3
SnOH 531 – 576
(Bu

3
Sn)
2
O 770
(Ph
3
Sn)
2
O 770
2.1.2 Mössbauer Spectroscopy
11, 2, 12–17
When the complexity of organotin structures was first becoming appreciated, Mössbauer
spectroscopy played a major part in elucidating the structures in the solid state. How-
ever, the spectra usually consist of singlets or doublets which are broad (typically
2.1 Physical Methods 15
0.4 mm s
–1
) compared with the normal range of isomer shifts [ca. 4 mm s
–1
for organo-
tin(IV) compounds], and data from different laboratories on the same compounds may
vary by ca. 0.2 mm s
–1
. The technique is used less now that the more discriminating
technique of high resolution solid state NMR spectroscopy has been developed, and
X-ray diffraction is more generally available for investigating crystalline samples. A
thorough, recent, review is available, which gives diagrams correlating the isomer shift
and quadrupole coupling with structural types.
17
The source of the γ-rays is the

119m
Sn isotope which is prepared by the (n,γ) reaction
of
118
Sn. It decays with a half life of 245 days to give the nuclear excited
119
Sn*. This
has a spin I of ±
3
/2, and a half life of 1.84 × 10
–8
s, and emits a γ-ray of 23.875 keV in its
transition to the ground state with spin I of ±
1
/2 . It is usually incorporated into barium
or calcium stannate, which give a line-width of about 0.33 mm s
–1
. Measurements are
usually carried out at 77 K, to increase the recoil-free fraction of the emission and ab-
sorption; for BaSnO
3
, this is 0.8 at 77 K, and 0.55 at 300 K.
The principal source of useful chemical information is the isomer shift (IS or δ) and
the quadrupole coupling (QC or ∆). Compilations of these data are available,
2, 12–18
and a
complete listing is given in the Mössbauer Effect References and Data Journal.
19, 20
The
symbols IS and QC are used in this text to avoid confusion with NMR chemical shifts.

Values of IS are usually referenced against SnO
2
or BaSnO
3
, which are the same within
experimental error (and all data in this book are quoted on this standard). For isomer
shifts which are given in the literature against other standards, the following corrections
should be applied: grey (α) tin, +2.10; white (β) tin, +2.70; Mg
2
Sn, +1.82; Pd/Sn +1.52
mm s
-1
. It is common practice now to analyse the spectra, particularly when peaks over-
lap, by computer curve-fitting programmes. Values for IS and QC (± ca. 0.2 mm s
–1
) for
a selection of organotin compounds are given in Table 2-3.
The isomer shift gives a measure of the s-electron density at the tin nucleus. As the
nucleus emits or absorbs the γ-ray, its radius changes, and the interaction with the
s-electrons which are close to the nucleus affects the separation between the ground state
and the excited state. A decrease in the s-electron density at the nucleus corresponds to a
more positive isomer shift.
The quadrupole coupling arises because the excited state with I of 3 + 2 has quadru-
polar charge separation, and this can interact with a local electric field gradient due to
the ligands about the tin. For example, a tetrahedral compound R
4
Sn, with zero field
gradient at the tin, will show only a singlet signal, but a compound R
3
SnX, with only

axial symmetry, will show the signal split into a doublet.
Thus organotin(II) compounds (Table 2-3) which frequently have the unshared elec-
tron pair in an orbital with substantial 5s character, usually show isomer shifts in the
range 2 to 4 mm s
–1
, whereas tin(IV) compounds show shifts in the range –0.5 to 2.5 mm
s
–1
. An elegant example of this is provided by bis(trimethylstannylcyclopentadi-
enyl)tin(II) (Me
3
Sn
IV
C
5
H
4
)
2
Sn
II
,
21
which presumably has an open-sandwich structure
similar to that of (C
5
H
5
)
2

Sn: itself, with C
2v
symmetry. For the Sn(IV) centre it shows a
singlet with IS 1.30, QC 0 mm s
–1
(cf. Me
4
Sn, IS 1.30, QC 0 mm s
–1
) and for the Sn(II)
centre it shows a doublet of half the intensity, with IS 3.58, QC 0.89 mm s
–1
(cf. Cp
2
Sn,
IS 3.72, QC 0.81 mm s
–1
).
Isomer shift values also depend on the electronegativity of the ligands, on the coordi-
nation number, and on the stereochemistry. Thus the series of alkylpentahalogeno-
stannates, BuSnX
n
Y
5–n
2–
shown in Table 2-4, may all be assumed to have similar octa-
hedral structures, and the value of IS falls with increasing electronegativity of X and Y,
i.e. as the ligand attracts electrons away from the tin.
22
A similar trend can be distin-

guished as the alkyl groups are varied in, for example, the tetrahedral compounds R
4
Sn,
indicating that the electron releasing power increases in the sequence Me < Et < Pr < Bu.